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Wireless and Optical Communications Conference (WOCC) is held once a year to exchange information among, mainly Chinese, professionals from China, Taiwan, Hong-Kong, Singapore, and the United States on the progress of technologies in the wireless and optical communications arena. The conference dated back to 1992, was initiated by Chinese professionals in the optical and wireless communication fields...
Cognitive radio (CR) is a promising dynamic spectrum access technique to improve the utilization of the licensed spectrum. In this paper, we investigate the medium access control (MAC) protocol for CR networks and propose a cognitive MAC using slotted Aloha to enable CR users to access spectrum holes in a licensed frequency band. In order to avoid the high computational complexities of traditional...
The incremental relay (INR) reception with multiple blind/fixed-gain AF relays and selection combining (SC) at the destination receiver is analyzed. The end-to-end performance of INR transmission is evaluated, where bit error rate (BER) of BPSK over i.i.d. Rayleigh fading channels is derived. Numerical results of the BER are presented for performance illustration and comparisons.
We reviewed our on-going effects in regenerative wavelength conversions. 40-Gb/s 3R-regeneratiave wavelength conversion was realized with EAM or SOA-DI as the decision gate. 100-Gb/s 2R-regenerative wavelength conversion was implemented by utilizing cross gain compression effect in SOA.
Recent emergence of coherent optical modem has solved a number of difficult problems in optical transmission, resulting in 10x increase in capacity. The latest research of super-channels further increases spectral efficiency and network flexibility.
Optical performance monitoring (OPM) is a potential mechanism to improve control of transmission and physical-layer fault management, which is essential for the operation of complex wavelength division multiplexing (WDM) transmission and switching systems. On the physical layer, the most important characteristics need to be monitored are chromatic dispersion (CD) and polarization mode dispersion (PMD)...
In this paper, we discuss recent progress in orthogonal frequency division multiplexing (OFDM)-based passive optical networks (PON) in a wavelength-reused optical network unit (ONU). To fully regenerate the uplink OFDMA and avoid large bandwidth of analog-to-digital converters (ADCs), a coherent receiver with selected sub-band technique is demonstrated.
We discuss the progress and advances in access network, which is considered as the “last-mile” connection between the end-user and the network. Different challenges and possible solutions of access network will be discussed, including the long-reach (LR) passive-optical-network (PON) and the short-reach (SR) wireless fiber-to-the-antenna (FTTA) system. Moreover, orthogonal-frequency-division-multiplexing...
This paper describes an innovative scheme of optical UNI converter. The enhanced converter solves the UNI interworking problem between the two kinds of models for control plane, ITU-T ASON/OIF UNI [1][2] and IETF GMPLS.
We propose and demonstrate an AC-power-signal-biased light-emitting-diode (LED) modulation. To minimize the signal distortion, the message signal is up-converted to a carrier of 400 KHz and 60 Hz AC-power signal are combined using our developed bias tee circuit. Measurement result shows a bit error rate (BER) below 10−8 at a transmission distance of 2 m. This technique is energy-efficient and compatible...
Searching for human actions in a large video collection is a frequent demand in our daily lives. However, it is often not well supported by current multimedia technologies. For example, by using the traditional text-based search methods, it is not quite straightforward to give proper keywords as query input if users are uncertain about the textual or verbal descriptions of interesting actions in their...
The queueing behavior of Hybrid Automatic Repeat reQuest (ARQ) system over wireless channel is analyzed in this paper. The wireless channel is modeled as a two-state Markovian process. Arriving packets, which are saved in a first-in-first-out (FIFO) buffer before being transmitted over a wireless channel, may be blocked due to buffer overflow. We obtain the closed-form expressions of queueing state...
This paper studies the performance of IEEE 802.15.4 MAC protocol in terms of throughput stability and energy consumption. We modeled it as a multi-queue single-server system and considered the service time distribution of head-of-line packets as a Markov Chain taking into account beacon-enable mode, acknowledgement and unsaturated traffic. We obtain the characteristic equation of network throughput...
In this work, we propose a novel modulation of four-band OFDM channels within 10-GHz bandwidth in 40-Gb/s PON with 128 ONUs. Here, we first propose using multi-band OFDM modulation format applying in −0.7 chirp parameter Mach-Zehnder modulator (MZM) to improve and compensate the fiber dispersion and RF fading effects. Moreover, −0.37 dB power penalty at FEC level (BER of 3.8×10−3) is also observed...
µ-law companding and de-companding, which enlarges small signals and compresses large signals, can work successfully in the CO-OFDM transmission system, and µ=1 is the optimal companding coefficient for PAPR reduction.
Efforts in reducing the power consumption of next-generation optical transceivers through the use of 10 Gb/s vertical cavity surface emitting lasers (VCSELs) in optical network units (ONUs) will be reviewed. Energy savings from a VCSEL ONU in power saving mode will be compared to an active distributed feedback laser based ONU, and will be analytically computed as a function of network parameters....
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